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The Natural Carcinogen “Cover-Up”

Any organic compound, when isolated, and fed at thousands of times the natural does, may have toxic or carcinogenic effects. does that mean that the compound, in a food, makes the food dangerous? No. If that were so then all foods, even organic foods, would have to be classified as carcinogenic (yet we know that this obviously is not so.)

The following is excerpted from http://fumento.com/alar/alar1.html


At one time, Dr. Bruce Ames was one of Efron’s key apocalyptics and a prime exponent of the “one molecule” method. He is a recipient of the most prestigious award for cancer research, the General Motors Cancer Research Foundation Prize, of the highest award in environmental achievement, the Tyler Prize, is a member of the National Academy of Sciences, and has served on the National Cancer Institute board of directors.

Bruce Ames, Senior Scientist at Childrens Hospital Oakland Research Institute (CHORI)

John Tierney, writing in Hippocrates Magazine in 1988, stated, “It was his laboratory procedure, the Ames [Mutagenic] Test, that alerted scientists and consumers to the dangers of hundreds of synthetic chemicals. He provided the evidence and occasionally, the rhetoric-that got things banned. He was a scientific hero of the environmental movement. “

Ames began to think about natural carcinogens and wrote Efron, who herself had discovered a mass of natural carcinogen literature in 1978, “Somehow, the theoreticians, the regulators, and the apocalyptic movement itself had misplaced them. The natural carcinogens were sitting there quietly in the literature on carcinogenesis, along with the synthetics. The only difference was that they had not been publicized.”

Ames decided to publicize those findings and the apocalyptics dropped him faster than an car of corn treated with DDT.

The apocalyptics had acknowledged the existence of a limited number of natural carcinogens, but a very limited number. Rachel Carson listed a few in Silent Spring, eg., ultraviolet rays, radioactive rocks, and arsenic. This dearth of natural carcinogens she attributed to evolutionary processes that allowed man’s physiology to co-exist with nature.

Most recently, Robert Bazell brought up this theory in the New Republic, where he noted approvingly the view that naturally occurring rodent carcinogens “probably don’t present any threat because humans have been eating these foods for thousands of years, and if there is a danger we have evolved a way to resist it.”

When I talked to NRDC Senior Attorney Al Meyerhoff, he gave me the same line, albeit pointing out that his expertise is in law and not the science aspects.

Gold, Ames, and others built a database of chemicals tested in lab animals and found that, even among natural chemicals, about half caused tumors in lab animals. These included chemicals found in table pepper, mushrooms, peanut butter, tea, and bread.

One hundred thirty-seven volatile natural chemicals have already been found in apple juice, of which only five have been tested for carcinogenicity. Three of these have been found to be carcinogenic in rats.

Now the apocalyptics were in a dilemma. By the same standard by which they were convicting synthetic chemicals as potentially lethal, the natural ones were proving just as bad.

As Ames and Gold point out, many foods have been introduced into our diets only in the last few hundred years, including such staples as coffee, tomatoes, and potatoes. Alcohol, aflatoxin, asbestos, radioactive rocks, and ultraviolet light have been around for several thousand years or since the earth’s beginning and have proved carcinogenic in man.

Many of the common heavy metals, such as cadmium, lead, nickel, beryllium, chromiurn, seleniuni, and arsenic, have been reported to be animal carcinogens. Finally, the evolutionary theory is valid only if cancer develops and kills before the reproductive period is complete.

In fact, environmentally induced cancer often takes decades to manifest, itself and in those cases in which there is solid evidence as to the cause, eg., tobacco and asbestos, it almost always strikes those past normal child-bearing years, hence would have no effect on evolutionary development.

Discussion of natural animal carcinogens undercuts the apocalyptics’ approach to risk. Plants produce toxins which protect them against fungi, insects, and predators such as man. Many of these natural pesticides have been discovered, and most species of plant contain a few dozen.

Of the natural toxins tested in animals, one half (25 of 50) have proved carcinogenic in MTD testing of lab animals, says Ames, as compared to 58 percent for synthetic chemicals.

It is probable, says Ames, that almost every plant product in the supermarket contains natural animal carcinogens.

Among those already identified as such are: bananas, broccoli, brussels sprouts, cabbage, carrots, celery, cocoa, grapefruit juice, honeydew melon, mushrooms, mustard, orange juice, peaches, black pepper, raspberries, turnips and apples, sans Alar. To worry about a substance present in apple juice in such small quantities that it can only be measured with the most advanced instruments seems fatuous indeed.

A few years ago, the American Cancer Society ran a series of commercials in which actors and actresses mocked the notion that “everything causes cancer.” Yet, if the results of mass-dose testing of laboratory animals are to be interpreted as applying to humans, they could prove that everything does cause cancer.

Indeed, the FDA was scared that the public would discover natural carcinogens, as evidenced by one FDA statement that Efron found buried in the middle of a long opinion on reportedly carcinogenic hair dyes, which read:

Indeed, a requirement for warnings on all foods that may contain an inherent carcinogenic ingredient or a carcinogenic contaminant (in contrast to a deliberately added carcinogenic substance) would apply to many, perhaps most, foods in a supermarket. Such warnings would be so numerous they would confuse the public, would not promote informed consumer decision-making, and would not advance the public health.

In order to establish a priority rating system for carcinogens similar to that already established for toxicity, Ames and Co. have set up what they call a HERP (human exposure dose/rodent potency dose) index, which rates the degree of carcinogenesis of various chemicals based on the degree to which they have caused tumors in lab animals.

Ames calls his rating system not a risk assessment but “an index of possible hazard,” noting that assigning a risk per million for any chemical is impossible, that the best one can do is compare one risk to the next.

Thus, a liter of tap water is rated 0.001 on the scale because it contains the rodent carcinogen chloroform. A 12-ounce bottle of beer is rated at 2.8 because it contains 18 milliliters of ethyl alcohol; conventional home air, which contains the animal carcinogen formaldehyde, is rated 0.6 per 14 hours of breathing; while the same amount of breathing in a mobile home will pull in enough formaldehyde to incur a rating of 2.1. EDB a grain fumigant banned by EPA in 1984, has a rating of .0004.

During the Alar scare, Ames and Lois Gold noted in a letter to Science that the UDMH in a six-ounce glass of apple juice has a HERP level of 0.0017 percent, less than one-tenth that of either a single raw mushroom a day or a single peanut butter sandwich.

It is one of the great ironies of the synthetic chemical phobia that some varieties of edible plants which have been bred to be naturally pest-resistant have ended up being withdrawn from the market because of acute toxicity to humans. Such was the case with one variety of potato. A specially bred pestresistant type of celery proved so toxic as to cause rashes on the hands of handlers, and upon analysis was found to have 6,200 parts per billion (ppb) of carcinogenic psoralens instead of the 800 ppb present in normal celery. Thus, there is a trade-off between natural pesticides and manmade ones-unless, of course, one doesn’t mind losing anywhere from 10 to 100 percent of ones crop to insects, weeds, and predators.

Ames estimates 99.9 percent of all pesticides are natural. We are ingesting about 1,000 times more natural than synthetic pesticides. It is reassuring, however, that many layers of general defenses in humans protect against toxins without distinguishing whether they are synthetic or natural. The apocalyptics have essentially grandfathered all natural animal carcinogens while slamming the door in the face of the synthesized ones.

Turncoat Ames has become a real thorn in the apocalyptics’ side. As a result of an apple industry backlash against CBS’s first Alar show, CBS did another show and interviewed Ames. Indeed, it spent the entire Ames portion trying to discredit him. At one point, reporter Ed Bradley said, “Dr. [William] Lijinksy disputes Ames’s claim that 99.9 percent of all carcinogens come from natural foods.” Such a claim would have been bizarre Bradley, who presumably had read Ames’s articles, must have known that in several of them he states, as have many others, that about 30 percent of human cancer cases are attributable to smoking alone.

At another point Ames says that compounds in celery and broccoli have been found to be carcinogenic. Bradley replies:

He believes further tests show he’s right. But for now, the national toxicology survey lists just 148 substances, and the compounds in celery and broccoli aren’t among them. One compound that is is the one produced by Alar.

Bradley was wrong. An April 1989 status report by the National Toxicology Program of the Public Health Service lists both allyl isothiocynanate and 8-methoxypsoralen as carcinogens, the former as “positive’ in male rats with the latter showing “clear evidence for carcinogenicity” in male rats. The first is found in broccoli, the second in celery. This material also appeared in Ames and Co.’s 1987 Science article which Ames claims to have sent to producer David Gelber but which, in any case, it was Gelber’s duty to read.

See this letter by Dr. Bruce Ames

Dr. Bruce Ames, noted biochemist and Chairman of the Department of Biochemistry at the University of California, Berkeley, was also interviewed by Mr. Bradley. His comments to “60 Minutes” were also distorted, as CBS did their best to discredit him. Specifically, the producers misquoted Dr. Ames — and then brought on Dr. William Lijinsky and allowed him, uncritically, to challenge the distorted statements attributed to Dr. Ames, without allowing Dr. Ames a rejoinder to clarify points. Below is the letter Dr. Ames wrote to Don Hewitt, “60 Minutes” producer, following the [14 May 1989] airing of the interview.


Learning Standards: AP Biology

Enduring Understanding 3B: Living things are composed of, and hence require, the elements and compounds that make up their biological components.

All life requires water and specific chemicals for its existence and survival, albeit in varying amounts and in different forms among organisms. The fundamental building blocks for all organisms are organic molecules composed of carbon, hydrogen and oxygen, and supplemented by other elements, especially nitrogen, phosphorus and sulfur. The structural characteristics and bonding possibilities of organic compounds — such as carbohydrates, lipids, proteins and nucleic acids — that are assembled from these constituents facilitate fundamental life processes, including energy transfer, molecular replication and biosynthesis, and construction of cell membranes. Some chemicals, however, interfere with such biochemical processes and can produce toxic effects when present above tolerance levels. Ongoing removal of micronutrients in agricultural soils requires an awareness of their importance in biological systems.


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